This invention relates to the field of organic chemistry and more particularly to ionic reactions of certain carbon tetrahalides with various organic compounds.
Carbon tetrachloride is generally considered to be a compound of limited chemical reactivity and has found application in a number of services which capitalize on its relative chemical inertness. Thus, for example, carbon tetrachloride is useful as a fire extinguishing agent, as a cleaning solvent and as a solvent for organic chemical reactions. For many years carbon tetrachloride found its principal application as a solvent, particularly for cleaning purposes. Recently, this market has been substantially closed off, however, due to government restrictions relating to the toxicity of carbon tetrachloride.
The use of carbon tetrachloride as a chemical intermediate has heretofore been restricted to a few specialized reactions. Commercial production of chloroform, for example, is carried out by reduction of carbon tetrachloride with iron and water. Compounds marketed under the trade designation "Freons" such as dichlorodifluoromethane and trichloromonofluoromethane are produced commercially by partially displacing chlorine from carbon tetrachloride with fluorine. The production of such "Freon" compounds has represented the principal commercial outlet for carbon tetrachloride for several years, and in recent years has provided the only major market for this material.
In 1876, Reimer and Tiemann discovered that phenol could be converted to ortho and parahydroxybenzaldehydes by reaction with chloroform in an aqueous alkaline medium. When they substituted carbon tetrachloride for chloroform, added ethanol and held the reaction mixture in a sealed tube at 100.degree.C. for 3 days, a mixture of ortho and parahydroxy benzoic acid was produced. The work of Reimer and Tiemann with carbon tetrahalides was limited to the particular reaction noted above, i.e., the addition of a carboxylic acid group para or ortho to a phenolic hydroxy group, using an ethanolic aqueous alkaline medium.
Because of its abundance and relative inexpensiveness, carbon tetrachloride is potentially a very attractive chemical intermediate. Prior to the present invention, however, this compound was considered to be a substantially inert material whose chemical activity was limited to certain particular reactions such as those outlined above.